There are innumerable situations which arise daily in which it is necessary or desirable to lift or move a heavy object. Various devices have been previously developed, of course, as aids in lifting or moving heavy objects. Included in a listing of such devices are winches of various types and descriptions.
Winches are used in various industries and applications today. Although a winch may be operated manually (e.g., a simple block and tackle), the preferred use is with the aid of a power source (e.g., an electric motor or gasoline engine).
There are many potential uses for a power winch in remote locations. For example, a power winch can be extremely useful in the field for moving timber, or towing a vehicle out of mud, snow or water, or moving large game animals which have been killed while hunting. Although electrically powered winches are available for mounting on the front of vehicles, such winches have several limitations.
For example, they can only be used when the vehicle engine is running. Thus, if the vehicle engine is disabled for any reason the winch cannot be used. Also, such winches are mounted on the front of the vehicle. Many times, however, it is necessary to tow or winch a vehicle rearwardly or even sideways to dislodge it.
Furthermore, such winches which are mounted on vehicles are of no use unless the vehicle can be driven to the location where the winch is needed. There are many situations in which it is not possible, because of the terrain, for a vehicle to be driven to the location where the winch is needed. For example, while hunting in mountainous or rough country it is often desirable to have a winch to move animals which have been killed, but it is not possible to drive to the location where the winch is required.
There are many situations where when using a winch it is necessary or desirable to be able to stop the winch during operation and yet hold a load without slippage. There are other situations where it is desirable to release the drum in a controlled manner in order to allow it to reverse slowly (e.g., to lower a load which has been raised with the winch).
It is also often necessary or desirable to be able to unwind the drum to pay out lengths of cable (e.g., in order to pull the free end of the cable from the drum to the object to be winched). Many winches do not include means for uncoupling the drum from the drive means for this purpose. Other winches may have this capability but are cumbersome or unsafe to use.
A further problem presented in the use of a winch system pertains to release of tension on the cable. In many situations it is necessary or desirable to be able to disconnect the cable from the object being winched but some tension remains on the cable. For example, the object being winched may roll or slide very slightly in a backward direction but is not in danger of rolling away or sliding away if disconnected from the winch. In this situation it can be difficult, if not impossible, to disconnect the cable from the object being winched.
A few portable power winches and hoists have been proposed. See, for example, U.S. Pat. Nos. 3,036,435; 3,322,398; 3,938,781; 4,145,028; 4,162,059; 4,196,889; 4,444,375; 4,552,340; and 4,623,124. These patents describe portable winches which are powered by gasoline engines. Such winches do not include the advantages exhibited by the power winch systems of the present invention. Also, many of such prior winch systems do not have good power-to-weight ratios, and they are limited in towing capacity. They also can be very slow in operation.
There is a very serious disadvantage associated with previous proposed winches, including portable winches, which utilize a centrifugal clutch on the power unit If the power unit should ever stop for any reason, or if its speed drops too low, the centrifugal clutch automatically disengages and the drum is free to rotate in reverse (i.e., the load on the cable pulls away from the winch and the drum unwinds very quickly as cable is pulled off of it). This presents a very dangerous situation. For example, if a load is being lifted off the ground when the clutch disengages, the load immediately falls downwardly and could injure someone. Even if a brake is included on a winch to slow or stop the drum from rotating in reverse, human reflexes are not fast enough to cause the brake to be engaged before the load has already fallen to the ground or increased in speed to the point where the brake won't hold it. If it is possible to lock a brake on the drum manually there is the very real danger of causing severe damage to the winch or the operator or both when the cable is finally suddenly stopped. These are safety hazards which can render use of such devices dangerous.
Other winch systems, hoists, transmissions, etc. are described in the following: U.S. Pat. Nos. 1,768,278; 1,931,655; 2,080,804; 2,309,285; 2,869,822; 3,291,452; 3,411,751; 3,871,7l4; 3,915,022; 4,109,799; 4,169,580; and 4,188,790. A winch system is also described in French Patent 474,214. However, such winch systems and hoists are not light-weight and are not portable systems which can be used at any desired remote location where a winch is needed. Furthermore, none of such patents describe a drum clutch assembly having the features and advantages provided by the present invention.
There has not heretofore been provided a portable, self-contained winch system of the type provided by the present invention. There has not heretofore been provided a winch system having the capabilities and advantages of the winch system of this invention.